What was found
DURING CRUISE FL350 AUTOPILOT B DISCONNECTED. REESTABLISHED AUTOPILOT B, DISCONNECTED A SECOND TIME. ESTABLISH AUTOPILOT A OPERATED NORMALLY. NO OTHER INDICATIONS, NEGATIVE TURBULENCE. GROUNDED - YES. INITIAL EVALUATION, PERFORMED DFCS BITE IAW B737-800 FIM 22-11 TASK 801, NO CURRENT FAULTS. PERFORMED ADDITIONAL TEST - AUTOPILOT (GROUP 11), NO FAULTS FOUND. A/P DISCONNECT FAULTS WERE PRESENT ON PREVIOUS LEG (LEG 01), PERFORMED LAND VERIFY TEST IAW AMM 22-11-00-700-801. PASSES ALL TESTS, NO FAULTS FOUND. NO A/C HISTORY FOR A/P CHANNEL B LAST 30 DAYS. A/C OK FOR SERVICE.